EP1165854B1 - Method and device for coating a product - Google Patents

Abstract

The invention relates to a method for coating a product (12) with a metallic layer (13), especially a high temperature component of a gas turbine, in a vacuum system (1). The invention also relates to a device for coating a product (12) with a metallic layer (13) in a vacuum system (1), comprising a coating chamber (3) and a post-heat retreatment chamber (5). According to a novel process control system concerning the temperature profile, a minimum temperature (Tmin) which is greater than room temperature (TR) is guaranteed at all times, especially after the metallic layer (13) has been applied to the product (12) and before the post-heat retreatment.

Description

The invention relates to a method for coating a Product with a metallic layer, in particular with a metallic oxidation protection layer, in a vacuum system. In the process, the product is placed in the vacuum system introduced and from room temperature to a product temperature heated, the metallic layer on the product applied and the coated product one Subsequent heat treatment. The invention relates furthermore a device for coating a product with a metallic layer in a vacuum system, the vacuum system having a coating chamber and a Heat treatment chamber includes.

They are coating systems for coating gas turbine blades known, e.g. an inline EB-PVD coating system by Interturbine Von Ardenne GmbH (EB-PVD: Electron Beam - Physical Vapor Deposition), where physical Evaporation process a ceramic layer the gas turbine blade is applied. Such a coating system can, for example, from one behind the other switched and with a transfer system for transportation the chambers connected to the turbine blades his. The first chamber serves as a loading chamber for Turbine blades. From the loading chamber, the Turbine blades in a second, to the loading chamber connected vacuum chamber transported and preheated there. Then it is transported on to a Process chamber in which a ceramic material, in particular zirconium oxide stabilized with yttrium, by means of electron beam evaporation is heated, melted and evaporated. The ceramic material condenses on the turbine blades and thus forms the ceramic coating. The so coated Turbine blades are transported further into a cooling chamber and chilled therein. The cooling takes place uncontrolled, especially uncontrolled, since the turbine blades left to their own devices in the cooling chamber and consequently their heat to the environment through heat radiation Deliver until they have cooled to room temperature.

A thermal insulation layer system is known from US Pat. No. 5,238,752 which is applied to a turbine blade is. The turbine blade consists of its base material made of a nickel-based superalloy on which a metallic Protective or connection layer of the type MCrAlY or PtAl is applied. M stands for nickel and / or Cobalt, Cr for chrome, Al for aluminum, Y for yttrium and Pt for platinum. Forms on this metallic bonding layer a thin layer of aluminum oxide on which the actual Ceramic thermal insulation layer made of yttrium stabilized Zirconia is applied. The coating of the Turbine blade here takes place by means of a physical one Evaporation process in which the ceramic material (Zirconium oxide) evaporated by bombardment with electron beams becomes. This coating process takes place in a vacuum chamber, the turbine blade being above a substrate heater by means of heat radiation to a temperature of about 1200 K. up to 1400 K, preferably about 1300 K, is heated.

The known methods and in the above described Facilities made layers on turbine blades are with regard to their service life, especially at Hot gas application when used in a gas turbine, still in need of improvement.

The invention has for its object a method for Coating a product with a metallic Specify layer. The durability of the metallic layer, especially against corrosive and oxidizing attacks, can be significantly improved. A Another object of the invention is a device for Coating a product with a metallic Specify layer. The device is intended to manufacture a high quality metallic layer on the Product may be possible.

According to the invention, the first object is achieved by a method according to claim 1 for coating a product with a metallic layer, in particular with a metallic Oxidation protection layer, in a vacuum system, in which the Product introduced into the vacuum system and from room temperature heated to a product temperature, the metallic one Layer applied to the product, the coated product is subjected to a heat treatment, the Post-heat treatment follows the application of the layer in such a way that the temperature of the product after application the layer and before the heat treatment at least is as large as a minimum temperature, being the minimum temperature is greater than room temperature.

The invention is based on the consideration that the Quality of a product based primarily on the base material applied metallic layer a special meaning due. Material properties as well as characteristic Layer properties, such as the homogeneity of the Layer, its connection to the substrate and the structure of the Boundary layer between layer and substrate are important quality features. These also have an impact on the connection and nature of other layers that may be in further coating processes applied to the primary layer become.

A metallic layer on a product, for example a metallic oxidation protection layer, is therefore yours Function, for example as a protective layer against corrosion and / or Oxidation, the more effective the better the above layer properties mentioned are realized. For the Service life of metallic layers on products that change for example under oxidizing or corrosive conditions in addition to the choice of materials is particularly important the connection of the layer to the base material of the product determinative. This is from the treatment of the product dependent in all phases of the manufacturing process. Here are chemical and physical - especially thermal Be aware of influences that may affect training and interfere with the connection of the layer. Dry Influences can be found by choosing suitable materials for all built-in parts of the equipment that are opposite the Layer materials should be as chemically inert as possible, be largely reduced. Physical conditions under which the manufacturing process of a layer takes place relate to litigation in its entirety, i.e. from the Product preparation, by applying the protective layer until further treatment of the product - usually a subsequent heat treatment - as well as all possible Intermediate steps. The control and organization of the Process control in all phases of the manufacturing process therefore very essential. Here are time-dependent and location-dependent thermodynamic process parameters, such as pressure and temperature, to which the product is subjected in the manufacturing process is taken into account. For example, due to the generally different coefficients of thermal expansion of base material and layer material the product temperature when applying the layer (coating temperature) and the temperature curve until the completion of a heat treatment influence of the coated product the formation of the boundary layer between the product surface and shift.

With the method is a quasi stationary process control in terms of temperature in all phases of the manufacturing process of the metallic layer. in this connection is after the application of the metallic layer on the Product and at any time before the heat treatment Minimum temperature of the product ensured, the larger than room temperature is.

In products, the high temperature components of gas turbines represent, such as gas turbine blades or heat shield elements of combustion chambers, this minimum temperature is preferably about 500 K, in particular about 900 K to 1400 K.

The process is characterized in that the product with its surroundings always close to a thermodynamic State of equilibrium. Temporal as well as spatial Temperature gradients, in particular temperature shocks avoided. Through this new way in litigation regarding the temperature profile it is possible to connect the metallic layer to the base material of the product to improve significantly in post-heat treatment. In which in this way adheres to the application of the metallic Subsequent post-heat treatment is by diffusion processes a firm connection between the base material and layered material, and a high quality Layer formed on the product.

The metallic layer is preferably applied on the product in a coating area and heat treatment in a heat treatment area. in this connection are the coating area and the heat treatment area different areas of the vacuum system. It is advantageous, the application of the metallic layer on the Product and post-heat treatment in the same vacuum system to carry out, but to separate them spatially, these process steps at slightly different temperatures be carried out and generally different process times exhibit. For example, applying one metallic layer on a gas turbine blade, in particular a metallic oxidation and corrosion protection layer, at a coating temperature of approximately 1100 K. up to 1200 K, while the heat treatment of the Gas turbine blade at a post heat treatment temperature from about 1200 K to 1500 K. The separation of coating area and heat treatment area affects favorable to the quality and reproducibility of the metallic Layers out. It is avoided that different Process steps with different process parameters in the same Area of a plant. this could practically only with a periodic change of the operating parameters the vacuum system, what the quality and Reproducibility of the layers impaired.

The coated product is automatically preferred by the coating area transferred to the heat treatment area. This procedure is with regard to an industrial one Production of the metallic layer is very advantageous. In a vacuum system in particular, an automatic, preferably electronically controlled transfer of the products, other known designs, for example with elaborate, manually operated manipulators and with sealed vacuum feedthroughs, far superior.

The heat-treated product is preferably checked cooled to room temperature. Is further preferred cooling is controlled or regulated to room temperature carried out. This is done in advance of a possible withdrawal of the product from the vacuum system. By control and control of the cooling process is avoided after Completion of post heat treatment the product in uncontrolled Way is cooled to room temperature, which turns out to be because of the then occurring thermal stresses between the metallic layer and the substrate adversely on the Layer properties could affect.

There is preferably a first number of products in the coating area and simultaneously a second number of Products in the heat treatment area, the second Number is greater than the first number. This procedure is very beneficial in terms of an industrial Series production of metallic layers on products. The metallic layer in the coating area is applied to products upset while at the same time in Post-treatment area Products of post-treatment be subjected. This makes production rational given by metallic layers on products. A continuous and simultaneous flow of products through the procedural steps is possible. In particular is the flow of products in this continuous process per unit of time compared to non-simultaneous process steps clearly increased. Due to the different Process durations of the individual process steps in the process more products of heat treatment subjected than at the same time in the coating area because the post-heat treatment process in general represents the time-limiting process. For example has applied a metallic layer to one Gas turbine blade, in particular the application of a metallic one Oxidation and corrosion protection layer, a process duration of about 30 minutes, while the heat treatment of the Gas turbine blade with approximately 60 min to 240 min considerable takes longer. By designing the vacuum system taking into account the respective process duration becomes a continuous one and simultaneous throughput of products ensured, and enables rational production.

A high-temperature component of a is preferred as the product Gas turbine, in particular a gas turbine blade or a Heat shield element of a combustion chamber used. More preferred is used as the base material for the high-temperature component a nickel, or iron or cobalt based superalloy used. A gas turbine blade is a high temperature component which is arranged in the hot gas duct of a gas turbine is. A distinction is made between turbine guide vanes and turbine rotor blades, the large thermal loads, in particular for gas turbines with high turbine inlet temperatures from e.g. over 1500 K, as well as corrosive and oxidizing Hot gas conditions are exposed. Therefore, for an appropriate alloy can be selected for the base material. An example of a high temperature resistant alloy this type with high creep resistance is based on nickel Inconel 713 C, which in its essential components consists of 73% Nickel, 13% chromium, 4.2% molybdenum and 2% niobium is.

An MCrAlX alloy is preferably used as the metallic layer used, where M is for one or more elements of the Group comprising iron, cobalt and nickel, Cr for chromium, Al for aluminum and X for one or more elements of the Group comprising yttrium, rhenium and the elements of Rare earth. This metallic layer is in the Coating area in a known manner by thermal Spraying using VPS (Vacuum Plasma Spraying) or LPPS (Low Pressure Plasma Spraying) on the product, in particular the high temperature component of a gas turbine. The MCrAlX layers are particularly suitable for high-temperature components in gas turbines with a base material a nickel, or iron or cobalt based superalloy suitable. They are suitable in stationary gas turbines and Aircraft engines with high turbine inlet temperature. she are also suitable as an adhesion promoter layer for the Applying further layers in other coating processes, such as for the manufacture of a ceramic Thermal insulation layer on a product using PVD (Physical Vapor Deposition).

The object directed to a device is invented solved by a device according to claim 9 for coating a Product with a metallic layer in a vacuum system, comprising a coating chamber and a heat treatment chamber, the heat post-treatment chamber is connected to the coating chamber in a vacuum-tight manner.

This makes it possible to apply the metallic Layer on a product and the subsequent heat treatment to be carried out in a plant. The vacuum-tight connection between the coating chamber and the heat treatment chamber ensures that the product to no Time during the process of the atmosphere, in particular is exposed to the oxygen in the air. Compared to conventional ones Attachments where the application of the layer and for heat after-treatment separately and with each other vacuum chambers not connected in a vacuum-tight manner are provided, the vacuum system is therefore superior.

There is preferably a heating device in the heat aftertreatment chamber intended. The heating device is realized in known configurations, for example by a radiant heating element for indirect radiant heating or by an electron beam gun for heating of the product by direct electron bombardment. For post heat treatment is the process management with regard to temperature of the product so that the product temperature to an intended value, the heat treatment temperature, established. By measuring the temperature of the Product and regulation of the heating power of the heating device, for example regulation of the radiation power of a radiant heating element using the heating current the post-heat treatment temperature is set.

A preheating chamber is preferably provided, that of the coating chamber is upstream and with this vacuum tight connected is. The preheating chamber is designed as a vacuum chamber and is part of the entire vacuum system for Coating a product with a metallic Layer. There is a heating device in the preheating chamber provided in a known manner, for example by a Radiant heating element for indirect radiant heating or through an electron beam gun to heat the product by direct electron bombardment. The On the one hand, the preheating chamber is used for receiving and preheating of the product from room temperature to a product temperature and on the other hand pretreatment and preparation of the product for subsequent process steps, in particular for the application of the metallic layer on the Product in the coating chamber. In the preheating chamber can also contain possible contaminants that may occur in the surface of the product are registered from which Degas the product. Impurities can cause the application the layer on the product and thus the quality of the Adversely affect the layer. Therefore, the preheating chamber meets in addition to pre-process heating, an important one Cleaning function for the product to be coated, so that a product with the degassing process accordingly cleanly prepared surface and well-defined product temperature is made.

A cooling chamber is preferably provided, that of the heat treatment chamber subordinate and with this vacuum tight connected is. After the heat treatment a product is heated. To continue the product to treat or lead to its purpose, one becomes bring it to room temperature in a suitable manner. To do this it can be cooled, for which purpose in conventional processes as well the external one, not coupled to a coating chamber Post-heat treatment chamber is used. In this the product is cooled in a controlled manner. On the other hand The controlled cooling process takes place in the vacuum system in a separate cooling chamber. The cooling chamber is there designed as a vacuum chamber and part of the whole Vacuum system. For controlled cooling of the product is a heating device in the cooling chamber intended. It ensures that the product during the Cooling process has a predetermined temperature. This is done the cooling of the product not too quickly through heat radiation or conduction to the environment, but quasi stationary, by gradually and controlling the temperature by regulating the heating power of the heating device is reduced to room temperature. The heating device is for example in the form of a known radiant heating element for indirect radiant heating of the Product exported. Additional known treatment facilities to cool the product, such as in the form of a Gas supply systems for inert cooling gases (e.g. argon) are in the cooling chamber predictable. In this embodiment the heated products in a well-dosed manner with one inert cooling gas is applied and checked to room temperature cooled. The cooling chamber advantageously serves at the same time as a removal chamber for the products.

The vacuum-tight connection between the coating chamber is preferred and the heat treatment chamber above made a lock chamber. Both the process times for applying the metallic layer to the product and for its heat treatment, as well as the respective process parameters, especially the coating temperature and the post-heat treatment temperature are different. To the For example, a metallic layer is applied on a gas turbine blade, especially a metallic one Oxidation and corrosion protection layer, at a coating temperature from about 1100 K to 1200 K. On the other hand post-heat treatment of the coated gas turbine blade at a significantly higher heat treatment temperature of 1200 K to 1500 K. It is therefore advisable to use these processes through appropriate facilities, here through a separate one Lock chamber realized, also spatially so far from each other to separate that mutual interaction is largely ruled out are. This configuration is also procedural Cheap. The lock chamber serves primarily the transfer of the products from the coating chamber to the heat treatment chamber. It is an integral part the vacuum system. Preference is given to the lock chamber a heating device is provided which has a predetermined Ensures product temperature during the transfer.

Advantageously, the product temperature in the Lock chamber during the transfer of the products from the coating chamber into the heat treatment chamber respective process temperatures are continuously adjusted. When using the vacuum system for industrial series production serves in a simultaneous continuous process the lock chamber as an important buffer system, in order to adapt the number of pieces to each other if necessary and thus a continuous flow of products to ensure.

A transfer system for automatic transfer is preferred the product from a vacuum chamber (preheating chamber, Coating chamber, lock chamber, heat treatment chamber, Cooling chamber) into another vacuum chamber the vacuum system.

Especially in a vacuum system, an automatic one is preferred electronically controlled transfer of products, other known designs, for example with complex, manually operated manipulators and with sealed vacuum feedthroughs. To in particular a continuous and automated flow of products are the vacuum chambers of Vacuum system (preheating chamber, coating chamber, lock chamber, Heat treatment chamber, cooling chamber) with one suitable transfer system. The transfer system assigns facilities for the takeover of products to Transport of goods and handover of goods arranged in the individual vacuum chambers are.

The coating chamber preferably has a first holding capacity and the heat treatment chamber a second Absorption capacity for products, with the second absorption capacity is larger than the first capacity. In general, the (average) number of products results in a vacuum chamber from the number of products supplied per unit of time multiplied by the (average) dwell time of the products in the vacuum chamber. In the ideal continuous Pass is the number of products fed the same for all vacuum chambers per unit of time. The (average) number of products in a vacuum chamber then determined by the residence time in this vacuum chamber. The Relative absorption capacity for products to be planned for the coating chamber and for the heat treatment chamber are then approximated by the respective process times given in these vacuum chambers. For applying one MCrAlX layer using the VPS or LPPS method on a gas turbine blade with a base material made of a nickel, Iron or cobalt based superalloys are typically obtained a process time of about 30 minutes, while the Post-treatment of the gas turbine blade a process time of about 120 minutes. As a result, the heat treatment chamber to dimension and design so that their absorption capacity for gas turbine blades at least is about four times the absorption capacity of the coating chamber. The vacuum system is designed so that they advantageously adjust the capacity the respective process times and therefore a continuous one and enables simultaneous throughput of products, which in turn is very cheap for industrial series production is.

FIG 1

eine schematische Darstellung in einem Längsschnitt einer Vakuumanlage zur Beschichtung von Erzeugnissen, beispielsweise von Gasturbinenschaufeln, mit einer metallischen Schicht,

FIG 2

ein Diagramm mit einem vereinfachten Temperaturverlauf für ein Erzeugnis gemäß einem herkömmlichen Verfahren und

FIG 3

ein Diagramm mit einem vereinfachten Temperaturverlauf für ein Erzeugnis gemäß dem erfindungsgemäßen Verfahren.

The device and the method for coating a product with a metallic layer in a vacuum system are explained in more detail by way of example using the exemplary embodiments shown in the drawing. Some of them show schematically and simplified:

FIG. 1

1 shows a schematic illustration in a longitudinal section of a vacuum system for coating products, for example gas turbine blades, with a metallic layer,

FIG 2

a diagram with a simplified temperature profile for a product according to a conventional method and

FIG 3

a diagram with a simplified temperature profile for a product according to the inventive method.

In Figure 1 is a schematic representation in one Longitudinal section of a vacuum system 1 for coating products 12, here for example of gas turbine blades 12, represented with a metallic layer 13. The vacuum system 1 has different vacuum chambers 2, 3, 4, 5, 6, one on top of the other following a preheating chamber 2, a coating chamber 3, a lock chamber 4, a heat treatment chamber 5 and a cooling chamber 6. Here is the coating chamber 3 vacuum-tight with the Heat treatment chamber 5 connected. The preheating chamber 2 is arranged upstream of the coating chamber 3 and is vacuum-tight with it connected. The cooling chamber 6 is the heat treatment chamber 5 downstream and with this vacuum tight connected. In the preheating chamber 2, the lock chamber 4, the Heat treatment chamber 5 and the cooling chamber 6 is respectively at least one heating device 7, 7A provided. In the exemplary embodiment shown, the heating devices are 7, 7A in the individual vacuum chambers 2, 4, 5, 6 as radiant heating elements for controlled heating of the arranged in the vacuum chambers gas turbine blades 12 a predetermined product temperature executed. In the vacuum chambers 2, 3, 4, 5, 6 a transfer system 8, 11 is provided, which in each case as the handover / takeover facility 11 and transport device 8 in the individual vacuum chambers 2, 3, 4, 5, 6 is executed. In the preheating chamber 2, the Lock chamber 4, the heat treatment chamber 5 and the Cooling chamber 6 are at least two gas turbine blades 12 arranged on the respective transport devices 8. The coating chamber 3 has a coating area 9, in which a coating device 14 and a rotatable about a longitudinal axis 17 holder 16 for gas turbine blades 12 are arranged. The coating facility 14 is here as VPS (Vacuum Plasma Spraying) -or LPPS (Low Pressure Plasma Spraying) device (plasma torch) for thermal spraying of coating material 15 - for example MCrAlX - on a gas turbine blade 12, executed. The coating device 14 also serves the heating of the gas turbine blade 12 to a predetermined Temperature of product. This is during a coating process by the hot process gases of the coating device 14 (Plasma torch) and through the gas turbine blade 12 striking coating material 15 guaranteed. A Gas turbine blade 12 is in the coating area 9 on the holder 17. The coating device 14 is above the gas turbine blade 12 in the coating area 9 arranged. In the heat treatment chamber 5 is a heat treatment area 10 is formed, in which a Number of coated gas turbine blades 12 with one metallic layer 13, in particular an MCrAlX layer, are on the transport device 8. Here is the number the gas turbine blades 12 in the heat treatment area 10 greater than the number of gas turbine blades 12 in the coating area 9. There are 10 in the after-treatment area two heating devices 7A are provided. A heating device 7A is above and the other heater 7A arranged below the gas turbine blades 12, so that this heats up the heat radiation Gas turbine blades 12 to a predetermined product temperature, which is the post-heat treatment temperature is. The vacuum chambers 2, 3, 4, 5, 6 of the vacuum system 1 are with a vacuum pump system, not shown in Figure 1 connected, which preferably consists of a diffusion pump, Valves and vacuum measuring devices as well as one Forevacuum pump exists, so that in the individual vacuum chambers 2, 3, 4, 5, 6 each required vacuum can be set is.

In the coating process for coating a product 12, which, for example, a gas turbine blade 12 is, with a metallic layer 13, in particular with a metallic MCrAlX oxidation protection layer, in a vacuum system 1, a gas turbine blade 12 is first inserted into the Preheating chamber 2 introduced and on the transport device 8 of the transfer system 8, 11 arranged. The preheating chamber 2 serves to hold and preheat the gas turbine blade 12. With the heating device provided in the preheating chamber 2 7, the gas turbine blade 12 of Room temperature to a product temperature, which is the coating temperature is heated. In the preheating chamber 2 the gas turbine blade 12 is pretreated and for subsequent ones Process steps, in particular for the application of the metallic layer 13 on the gas turbine blade 12 in the Coating chamber 3, prepared. In the preheating chamber 2 can also contain possible contaminants that may occur in the surface of the gas turbine blade 12 is entered, outgas from the gas turbine blade 12. Therefore, the Pre-heating chamber 2 in addition to the pre-process heating at the same time an important cleaning function for those to be coated Gas turbine blade 12. It is here after the heating and Degassing process with a gas turbine blade 12 accordingly cleanly prepared surface and well-defined product temperature, which is the coating temperature. Then the gas turbine blade 12 is also the transfer system 8, 11 from the preheating chamber 2 in the Coating area 9 of the coating chamber 3 automatically transferred and on a mobile, here on the one Longitudinal axis 17 rotatable bracket 16 is arranged. In the coating chamber 3 becomes a during the coating process metallic layer 13, for example an MCrAlX oxidation protection layer, applied to the gas turbine blade 12. The coating material 15 (MCrAlX) is for example by thermal spraying using the methods VPS-Vacuum Plasma Spraying or LPPS-Low Pressure Plasma Spraying on the surface of around the longitudinal axis 17 moved, in this case rotating about the longitudinal axis 17, Gas turbine blade 12 applied. The process time for that Applying this layer 13 takes about 30 minutes. While this time period, the gas turbine blade 12 is through the process-related heat input into the gas turbine blade 12 kept at a coating temperature that at is about 1100 K to 1200 K. This is where the heating takes place the gas turbine blade 12 by the hot process gases Coating device 14 (plasma torch) and through that the coating material impinging on the gas turbine blade 12 15. After the application of the metallic layer 13 the gas turbine blade 12 becomes this from the coating area 9 in the heat treatment area 10 with the transfer system 8, 11 transferred automatically. This transfer takes place via the lock chamber 4. In the lock chamber 4 is the gas turbine blade 12, by means of the arranged there Heating device 7, at a predetermined product temperature kept that is always greater than a minimum temperature is. The minimum temperature is higher as room temperature and is preferably 500 K, in particular between about 900 K to 1400 K. After the transfer is in the heat treatment area 10 with a gas turbine blade 12 provided with metallic layer 13 undergo post-heat treatment at a post-heat treatment temperature from about 1200 K to 1500 K. For this purpose, the gas turbine blade 12 with the Heating devices 7A to the predetermined heat treatment temperature brought and on this for a period of time held. The process time here is, for example 120 min (see also descriptions for Figure 2 and Figure 3). This creates a fixed connection (diffusion connection) between the metallic layer 13 and the base material the gas turbine blade 12 manufactured. After heat treatment the gas turbine blade 12 from the heat treatment chamber 5 into the cooling chamber 6 automatically transferred. After heat treatment of a gas turbine blade 12 this is heated to a temperature. To the Gas turbine blade 12 to treat further or their determination it is supplied in a suitable manner at room temperature brought. To do this, it must be cooled. In conventional methods, this is also in the external Heat treatment chamber performed that is not connected to a Coating chamber is vacuum-coupled. In the In contrast, the controlled cooling process takes place in a vacuum system in the separate cooling chamber 6. For controlled cooling the gas turbine blade 12 in the cooling chamber 6 is one Heating device 7 is provided. This ensures that the gas turbine blade 12 during the cooling process has a predetermined temperature. This cools down the Gas turbine blade 12 not too quickly through heat radiation or heat conduction to the environment, but rather stationary, by gradually and controlling the temperature through Control or regulation of the heating power of the heating device 7 until reduced to room temperature. After this the gas turbine blade 12 in the cooling chamber 6 in a controlled manner Cooled to room temperature, it will taken from the cooling chamber 6.

This is just an example of a product 12, in particular a gas turbine blade 12, described method for coating of a product 12 with a metallic Layer 13 is characterized in that it is a continuous and simultaneous continuous process is designed. In this way, multiple products can be 12 different Carry out process steps simultaneously and continuously. This is illustrated in FIG. 1 by the fact that, for example a gas turbine blade 12 in the coating area 9 and simultaneously a larger number of gas turbine blades 12 each in the preheating chamber 2, in the lock chamber 4, in the heat treatment area 10 and in the cooling chamber 6 are located. Accordingly, on gas turbine blades 12 a metallic layer 13 in the coating area 9 applied while simultaneously in the heat treatment area 10 gas turbine blades provided with a metallic layer 13 12 are subjected to a heat treatment, and while at the same time in the preheating chamber 2 gas turbine blades 12 are pretreated, and at the same time in the cooling chamber 6 cooled gas turbine blades 12 in a controlled manner be, and at the same time in the lock chamber 4 gas turbine blades 12 are transferred. A continuous one and simultaneous passage of gas turbine blades 12 through the different process steps are possible. In particular is the passage of gas turbine blades in this continuous process 12 per unit of time versus non-simultaneous and / or non-continuous processes significantly increased. Due to the different process times of the individual Process steps, the process involves more gas turbine blades 12 subjected to a heat treatment, as are coated at the same time in the coating area 9, since the post-heat treatment process is generally the represents a time-limiting process. By interpreting the Vacuum system 1 taking into account the respective process times becomes a continuous and simultaneous run of Products 12 ensured, and rational production of metallic layers 13 on products 12 allows. The method is suitable in addition to the coating of gas turbine blades 12 also for coating other high temperature components of a gas turbine, for example for heat shield elements of a combustion chamber.

In the following figures the process control is regarding the temperature profile according to a conventional method (Figure 2) and according to the inventive method (Figure 3) compared and explained in more detail. Doing so for illustration purposes sometimes with reference numerals from FIG. 1 directed.

FIG. 2 shows a diagram in which the temperature is plotted over time for a product 12, in particular for a gas turbine blade, in accordance with a conventional coating method. The time is plotted on the X-axis of the diagram and the temperature T on the Y-axis of the diagram, which the product 12 has at a specific time t during the process. The product temperature T as a function of time t is shown in the diagram as a curve T ₁ (t). The product 12 is first heated linearly from room temperature T _R to a product temperature T, which is the coating temperature T _C. During the application of the metallic layer 13 to the product 12, the temperature for the coating process duration Δt _{C is kept} at the coating temperature T _C. Subsequently, the product 12 is cooled from the coating temperature T _C to room temperature T _R. Thereafter, the product 12 is usually removed from the coating chamber 3, stored in a suitable manner, and fed to a post-treatment chamber 5 for post-treatment at an indefinite point in time. The post-treatment of the product 12 consequently does not take place immediately after the application of the metallic layer 13. In order to illustrate this, the time axis t is interrupted in FIG. 2 after cooling to room temperature T _R and before the start of the heat treatment. So this is not a continuous process. The product 12 is finally subjected to a post-heat treatment. For this purpose, the product 12 is first heated from room temperature T _R (linear) to a product temperature T, which is the post-treatment temperature T _H. This is greater than the coating _temperature T _C. Since the post-treatment generally has a longer process time than the application of the metallic layer 13, the post-treatment process time Δt _H during which the product is at the post-treatment temperature T _H is correspondingly greater than the coating process time Δt _C. For example, for post-heat treatment of products 12, which are gas turbine blades, the post-heat treatment process time Δt _{H is} approximately four times as long as the coating process time Δt _C. After the post-heat treatment, the product 12 is cooled again from the post-heat treatment temperature T _H to room temperature T _R. The process control with regard to the temperature profile in a conventional method is characterized in that the product 12 is cooled to room temperature T _R between the application of the metallic layer 13 and the heat aftertreatment.

FIG. 3 shows a diagram with a temperature profile for a product 12, in particular for a gas turbine blade, according to the method according to the invention. The time t is plotted on the X axis of the diagram, while the product temperature T is plotted on the Y axis of the diagram, which the product T has at a specific time t. The product temperature T as a function of time t is illustrated in the diagram by the corresponding curve T ₂ (t). With this temperature profile, the product 12 is first linearly heated from room temperature T _R to a product temperature T, which is the coating temperature T _C. During the application of the metallic layer 13 to the product 12, the temperature for the coating process duration Δt _{C is kept} at the coating temperature T _C. For products 12, which represent gas turbine blades, for example, which are provided with an MCrAlX layer, the coating _temperature T _{C is} approximately 1100 K to 1200 K. Immediately after the actual coating process, the product 12 is moved continuously from the coating area 9 into the heat treatment area 10 through the lock chamber 4 transfers what may - as illustrated - be associated with a change in the temperature of the product 12, generally a decrease in the temperature. The temperature profile in this process step is carried out in such a way that the possible temperature decrease of the product 12 from the coating temperature T _{H is} limited to a minimum temperature T _min which is greater than room temperature T _R. In the case of gas turbine blades, the minimum temperature T _{min is} preferably greater than 500 K, in particular between approximately 900 K to 1400 K. The product 12 is then heated for post-treatment to a product temperature T, which is the post-treatment temperature T _H and which, for example, for gas turbine blades is approximately 1200 K to 1500 K. The post-heat treatment takes place at the post-heat treatment temperature T _H at which the product 12 is held for a post-heat treatment process duration Δt _H. The post-treatment process time Δt _H is greater than the coating process time Δt _C. After the post-heat treatment, the product 12 is cooled from the post-heat treatment temperature T _H to room temperature T _R. The time-dependent temperature profile of the product 12 according to this method has a continuous curve T ₂ (t), which in particular connects the plateau region with the coating _temperature T _C and the subsequent plateau region with the post-treatment temperature T _H in a controlled manner and continuously. The connection is made in such a way that a minimum temperature T _{min of} the product 12 is ensured at all times, the product 12 expressly not being cooled to room temperature T _R and / or being exposed to the atmosphere. This new process control with regard to the temperature profile makes it possible to significantly improve the connection of the metallic layer 13 to the base material of the product 12 in the post-heat treatment. The product 12 and its surroundings are always close to a thermodynamic equilibrium state. Temporal and spatial temperature gradients, in particular harmful temperature shocks due to cooling to room temperature T _R , are avoided, which has a very advantageous effect on the quality of the metallic layer.

Claims (17)

1. Method of coating a gas turbine blade (12) with a metallic anti-oxidation coating (13) in a vacuum plant (1), in which method

   (a) the gas turbine blade (12) is fed into the vacuum plant (1) and heated from room temperature (T_R) to a gas turbine blade temperature (T),

   (b) the metallic oxidation coating (13) is applied to the gas turbine blade (12) in a coating region (9), and

   (c) the coated gas turbine blade (12) is subjected to a postheat treatment in a heat treatment region (10),

   characterized in that the postheat treatment follows the application of the coating (13) in such a way that the temperature of the gas turbine blade (12) after the application of the coating (13) and before the postheat treatment is at least as high as a minimum temperature (T_min), the minimum temperature (T_min) being higher than room temperature (T_R), and in that the coated gas turbine blade (12), in an intermediate step within the vacuum plant (1), is transferred from the coating region (9) into the postheat treatment region (10).
2. Method according to Claim 1, characterized in that the coated gas turbine blade (12), in the intermediate step, is kept at a temperature higher than the minimum temperature (T_min).
3. Method according to Claim 1 or 2, characterized in that the minimum temperature (T_min) is about 500 K, in particular about 900 K to 1400 K.
4. Method according to Claim 1, characterized in that the application of the metallic coating (13) to the gas turbine blade (12) is effected in a coating region (9) and the postheat treatment is effected in a postheat treatment region (10), the coating region (9) and the postheat treatment region (10) being different regions of the vacuum plant (1).
5. Method according to Claim 4, characterized in that the coated gas turbine blade (12) is transferred automatically from the coating region (9) into the postheat treatment region (13).
6. Method according to Claim 1, 4 or 5, characterized in that the gas turbine blade (12) subjected to postheat treatment is cooled down to room temperature (T_R) in a controlled manner.
7. Method according to one of Claims 4, 5 or 6, characterized in that a first number of gas turbine blades (12) is located in the coating region (9) and simultaneously a second number of gas turbine blades (12) is located in the postheat treatment region (10), the second number being larger than the first number.
8. Method according to one of the preceding claims, characterized in that the parent material used for the gas turbine blade (12) is a nickel- or iron- or cobalt-base superalloy.
9. Method according to one of the preceding claims, characterized in that the metallic coating (13) used is an MCrAlX alloy, where M stands for one or more elements of the group comprising iron, cobalt and nickel, Cr stands for chromium, Al stands for aluminium, and X stands for one or more elements of the group comprising yttrium, rhenium and the elements of the rare earths.
10. Apparatus for coating a gas turbine blade (12) with a metallic anti-oxidation coating (13) in a vacuum plant (1), comprising a coating chamber (3) and a postheat treatment chamber (5), characterized in that the postheat treatment chamber (5) is connected to the coating chamber (3) in a vacuum-tight manner.
11. Apparatus according to Claim 10, characterized in that a heating device (7A) is provided in the postheat treatment chamber (5).
12. Apparatus according to Claim 10 or 11, characterized in that a preheating chamber (2) is provided, this preheating chamber (2) being arranged upstream of the coating chamber (3) and being connected to the latter in a vacuum-tight manner.
13. Apparatus according to Claim 10, 11 or 12, characterized in that a cooling chamber (6) is provided, this cooling chamber (6) being arranged downstream of the postheat treatment chamber (5) and being connected to the latter in a vacuum-tight manner.
14. Apparatus according to Claim 10, 11, 12 or 13, characterized in that the vacuum-tight connection between the coating chamber (3) and the postheat treatment chamber (5) is produced via a lock chamber (4).
15. Apparatus according to Claim 14, characterized in that a heating device (7) is provided in the lock chamber (4).
16. Apparatus according to one of Claims 10 to 15, characterized in that a transfer system (8, 11) is provided for the automatic transfer of the gas turbine blade (12) from a vacuum chamber (2, 3, 4, 5, 6) into another vacuum chamber (2, 3, 4, 5, 6) of the vacuum plant (1).
17. Apparatus according to one of Claims 10 to 16, characterized in that the coating chamber (3) has a first receiving capacity and the postheat treatment chamber (5) has a second receiving capacity for gas turbine blades (12), the second receiving capacity being greater than the first receiving capacity.

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